Captivate Unused Actions

Unfortunately this is another area where Captivate needs to be improved.

In order to completely be able to get rid of certain Advanced Actions you often need to go into them BEFORE deleting and disconnect them from all user variables, slides and slide objects.  Only THEN can you delete the actions.

So, unfortunately in your case, even though you may have already deleted the relevant slides and all objects, the action may still persist because Captivate still seems to THINK it's still linked to something else.  I find this issue can also be due to spawning projects from CPTL templates where the Advanced Actions are already set up.  The CPTX seems to be caching the references to the CPTL somewhere internally and won't allow you to delete certain objects, variables or Advanced Actions.  If you check the Usage button it will often name the template as still being connected to the objects.